Forum Discussion
MariKaa
Apr 04, 2026Copper Contributor
.xlsm files fail to open
.xlsm files fail to open with “file or extension not valid” + Excel reports file is opened in another application Hello, I am experiencing a persistent issue where any .xlsm file (including brand‑n...
Kidd_Ip
May 22, 2026MVP
I believed it may related to mismatch between the file extension and the actual file format, or the workbook is being locked by residual cache/association issues.