The resolution report, delivered monthly, gives publishers valuable insight into DOI usage. It also is a good resource for identifying potential problems with either depositing practices or linking. The resolution failure rate is of particular interest as it allows a publisher to compare their failure rate with that of other publisher members. The ideal failure rate is 0% but realistically 2-3% is the norm. Publishers who are new to Crossref or who have created a small number of DOIs may have a high failure percentage (for example, a publisher with 1 failure and 9 successes will have a 10% failure rate).
A .csv file containing a list of all failed DOI resolution attempts for the month is attached to each report. This file should be reviewed to identify problems with both linking and deposits. Any DOIs with a high number of failures should be examined closely. Significant changes in your resolution failure rate should be taken seriously as well.
- If you have a high number of failures for a DOI you have not published, Google the DOI to see if it is readily available online - it is possible that the DOI is being linked incorrectly.
- If an active DOI appears on your failed DOI list, review when the DOI was deposited. For example, if the DOI was deposited on the 18th, any resolution attempts prior to the 18th will appear on your report.
- The Handle resolver supports URL-encoded DOIs.The resolution logs sometimes misrepresent the encoded characters. As a result, some badly encoded DOIs will appear in your resolution log as correctly encoded DOIs. This typically happens when an already-encoded DOI is mistakenly encoded again. For example, DOI 10.5555/example would be correctly encoded as 10.5555%2Fexample (the / is encoded as %2F). If the DOI is encoded again, the % in the DOI becomes %25, making the DOI 10.5555%252Fexample. This DOI will not resolve but will appear in the failed DOI report as 10.5555%2Fexample (a valid DOI).
Crossref can run additional reports if necessary - contact support for details
Not all DOIs included in the failed DOI .csv are legitimate DOIs ( DOIs that have been published). Possible reasons for DOI failure include:
- Undeposited DOI: a DOI has been distributed but not deposited - any DOIs that have been published should be deposited immediately to prevent future resolution failures.
- User error: a user can sometimes make mistakes when typing or cutting-and-pasting DOIs. These failures will appear on your report and for the most part can be ignored - if your report frequently includes what you determine to be user errors, review how your DOIs are displayed. Some common user errors are:
- 0 vs. 0, l vs. 1: Most DOI resolutions are generated by users clicking on a link, but (particularly for those of you who publish DOIs in print) users do type them in. If your DOI failures often contain DOIs with 0 being confused with O, or l with 1, consider changing your DOI suffix. Long strings of letters and numbers can cause problems as well.
- DOIs ending with .: One of the more common DOI failures is an otherwise viable DOI with a '.' appended. These usually are linked from references that end with a '.'
- DOIs with special characters instead of -: this commonly happens when a user cut-and-pastes a DOI from a PDF.
- DOIs with special characters: end users often are not aware of problems caused by linking with special characters such as <,>, #, and +. Crossref does not currently accept deposits with special characters but did in the past.
- DOI publication and deposit are out of sync: if you publish DOIs (print or online) prior to depositing them, any resolution attempts will appear in the report. DOIs should be published and deposited as close to simultaneously as possible. It's often not possible to do so, but the interval should be hours or a day, not days or weeks.
- Linking issues: occasionally a DOI is the victim of a bad link - if the link is under your control, please change it. If not, alert the link creator whenever possible.